For years, officials insisted the U.S. was winning in Vietnam. In truth, this compelling documentary says, President Johnson always had doubts; we hear him on the phone, admitting his fears.

This film ends too abruptly in 1968. PBS has viewed Vietnam with more depth and has an upcoming Ken Burns project. Still, CNN – helped by ex-soldiers, reporters and historians – skillfully brings perspective.

TONIGHT’S MIGHT-SEE: “Rookie Blue” season-opener, 8 and 9 p.m., ABC.

For four summers, this Canadian drama has juggled solid crime stories with the soap-style lives of telegenic young cops. It has succeeded, partly due to the appeal of Missy Peragrym as Andy.

Last season ended with a shoot-out; now Sam and Chloe are hospitalizes and others are confused. Dov is in a funk after meeting the estranged husband Chloe hadn’t mentioned. When Andy tries to talk him through it, they end up in the middle of a hold-up. It’s a good hour; the second one is merely OK.

TONIGHT’S ALTERNATIVE: “Dominion” debut, 8-9:30 p.m., CNN.

The 2010 movie “Legion” saw modern Earth as a battleground between archangels, good (Michael) and evil (Gabriel). This series jumps ahead 25 years: Vile creatures roam; Earthlings huddle in fortified cities.

The best-equipped city is Vega (formerly Las Vegas), where Michael lives. It’s led by a general (Alan Dale) and an ambitious senator (Anthony Head), whose daughter and son, respectively, hope for the emergence of a “chosen” child, now in his mid-20s. Then there’s the angry soldier (Christopher Egan) who dismisses much of this. “Dominion” takes a while, but builds into an epic series worth trying.

“The Big Bang Theory,” 7 p.m., CBS. With “Big Bang” being a Critics Choice leader with five nominations (including best comedy series), we can sample this rerun. Sheldon and Penny (Jim Parsons and Kaley Cuoco, both nominees) spend time together, after she quits her job and he’s forced to take a vacation.

“Defiance” season-opener, 7 p.m., Syfy. The second season finds big changes in the mining town where people link against alien forces. Amanda (Julie Benz) is running a saloon, with creepy Niles replacing her as mayor. Nolan searches for Stahma, the tough alien he’s raised since girlhood. She offers some interesting surprises and questions, in an adequate episode.

“Gang Related,” 8 p.m., Fox. Embittered and paraplegic, Carlos launches his own crime scheme, with nasty results. On the plus side, there are moments adding depth to Javier (Carlos’s father) and to Kang, one of the cops. On the minus, a plot twist involving Green (another cop) feels contrived.

“Rectify,” 8 p.m., Sundance. The terrific first season focused on an ex-con, who’s at home while his murder conviction may get a new trial. Tonight, people react to the fierce beating he received.